Events from last week highlight two very different faces of the Syrian intervention movement and how each is evolving: Senator John McCain’s visit with rebel leaders, and the as yet unconfirmed report of an American combatant’s death. These developments have attracted increased attention to the possibility of U.S. intervention in Syria, a prospect which seemed unlikely just months ago.

The Obama administration remains determined to stay out of another potentially entangling Middle East conflict but has admitted that if the Assad regime is found to have used chemical weapons against opposition forces and/or civilians, such action would be a “game-changer.” Officially, the jury is still out as to whether or not Bashar al-Assad has used chemical weapons, and, in the meantime, the prolonged fighting and lack of international consensus are causing some groups (and individuals) to take action.

Senator John McCain has long been an outspoken proponent of intervention in Syria, but his efforts reached a new level last week. After attending an economic forum in Turkey on May 27, the Senator hopped across the border to Syria to meet with rebel leaders.

Here’s what is known about Senator McCain’s trip:

• The Senator spent several hours inside Syria meeting with General Salim Idris, chief of staff of the Free Syrian Army, as well as other rebel commanders.
• The rebels’ requests echoed measures that the Senator has repeatedly called for: air strikes against Hezbollah and government targets, arms for the insurgents, and a no-fly zone.
• The White House and the State Department were aware of McCain’s trip.

On the same day, the E.U. voted to lift an arms embargo on the Syrian opposition movement. This decision “disappointed” the Russians, who are threatening to derail the upcoming Geneva peace summit as a result.

Meanwhile, Moscow plans to follow through on the delivery of S-300 air defense missiles to al-Assad, claiming that they signed the contract for these missiles years earlier. These arms issues may pose an insurmountable obstacle to international cooperation.

The intervention movement also has a smaller, more extreme contingent: foreign fighters. Days later, reports surfaced of an American woman killed in Syria, 33-year old Nicole Mannsfield. If these reports are confirmed, Mannsfield is the first American combatant killed in the Syrian civil war. Mannsfield’s case is a fairly isolated occurrence – only one other American is known to have fought in Syria – but it adds to the larger debate over foreign fighters in Syria, indicating that recruitment is taking place at the grassroots level.

As the international community tries to discern who exactly makes up the rebel movement, it has become apparent that fighters have come from abroad to join the opposition – some of whom may be associated with terrorists, insurgents, or other radicalized groups. The uncertainty surrounding the affiliations of foreign fighters has been a major point of contention in the debate over providing support for rebel forces.

Considering the outcomes of “Arab Spring” uprisings in Libya and Egypt, as well as the wars in Iraq and Afghanistan, Obama’s caution over Syria is warranted. At this point, however, the violence shows no signs of stopping or even deescalating. Should diplomatic efforts fail (and they very well may), it will be up to the U.S. to lead the search for a strategy that alleviates the humanitarian crisis, eliminates Assad’s chemical weapons stockpile, and prevents Syria from becoming a terrorist stronghold. To make the best case for intervention, proponents should advocate a multilateral mission that requires minimal U.S. commitment. Although it differs somewhat from Syria, Bosnia is proof that this type of intervention can work.

The pro-intervention movement still has much convincing to do. By presenting a clear and unified strategy that addresses humanitarian and security concerns, the interventionists may be able to add to their ranks and convince Obama to be the “game-changer” instead of waiting for it to happen.